1. Technical Field
The present invention relates to a V-cutter used in manufacturing a light guide panel for a backlight unit in a liquid crystal display (LCD), and more particularly, to a kit with a plurality of pins for a V-cutter designed to form a plurality of V-shaped grooves spaced apart by a desired interval on the light guide panel.
2. Background Art
An LCD (liquid crystal display) unit, such as may be used in a flat panel computer screen, is not self-illuminating, and therefore requires a separate backlight unit with a light source behind the LCD unit.
Because a large investment in the LCD industry has been made in Japan, Korea, and Taiwan, demand for the LCD unit, backlight unit, and other related parts is increasing.
Recently, LCD units have become smaller and lighter. Accordingly, backlight units for the new LCD units have become thinner and lighter through the use of a side light configuration.
In a backlight unit with a side light configuration, the emitted light by a light source to the side of the light guide panel is dispersed to have a uniform luminance across the light guide panel, so that a regular pattern is formed on the bottom of the light guide panel.
Since the light source for emitting the light is disposed on the side of the light guide panel, the pattern with a wider interval is disposed at the area adjacent to the light source and the pattern with a narrower interval is disposed at the area far from the light source, in order to keep the luminance uniform across the surface of the light guide panel.
The pattern on the bottom of the light guide panel used to disperse the light from the side-mounted light source may be, for example, a known groove pattern type for a TFT-LCD monitor or a notebook computer screen.
FIG. 1 is a longitudinal sectional view of one example of a backlight unit with light guide panels disposed in a groove pattern in which the upper portion is a plane of the light guide panel on which the liquid display elements are disposed, and the lower portion is a bottom of the light guide panel.
On a side of the light guide panel 1 made of a transmission material, such as acrylic or the like, a light source 2 for illuminating the LCD unit is disposed. At the bottom of the light guide panel a plurality of V-shaped grooves 3, or grooves 3, are formed. The V-shaped grooves 3 serve to uniformly disperse the light emitted by the light source 2. A reflecting seat 4 constructed of a reflective material, such as PET, is attached thereon.
The grooves 3 formed on the bottom on the light guide panel 1 disperse the emitted light from the light source 2 across the upper surface of the light guide panel. The grooves 3 are separated by a wider interval in vicinity of the light source 2 because the light against the nearer grooves 3 has a comparatively high luminance. The grooves 3 further from the light source 2 are spaced apart by a narrower interval so that the luminance can be uniformly maintained on the plane of the light guide panel 1.
In the backlight unit, light from the light source is reflected between the LCD unit and the reflective seat 4 until it strikes one of the V-shaped grooves 3. The V-shaped grooves 3 refract the light at such an angle that the light disperses on the inner surface of the light guide panel and impinges relatively directly against the LCD unit, as depicted by the arrows in FIG. 1. The refracted light then provides backlighting for the LCD unit disposed on the upper surface of the light guide panel.
The light emitted by the light source 2 is uniformly refracted by V-shaped grooves 3, which are formed on the plane of the light guide panel 1 by a device called a xe2x80x9cV-cutterxe2x80x9d.
Conventionally, a V-cutter has a lift piece disposed on slider that moves horizontally (along the X-axis) along a guide rail. The lift piece may be vertically actuated by a controller, such as a hydraulic or mechanical cylinder or a step motor. A pin for forming the V-shaped grooves 3 on the light guide panel may be affixed to the bottom surface of the lift piece.
The V-shaped grooves 3 are formed by, first, fixing the light guide panel on a table and moving the slider along the guide rail. The lift piece is lowered to a bottom dead center position by the controller so that the pin forms one of the V-shaped grooves 3 as it moves across the light guide panel.
After formation of the first of the V-shaped grooves 3, the table moves indexes the light guide panel to a different position with respect to the lift piece to form another of the grooves 3 at a pitch, or displacement from the first groove. This process repeats until all of the V-shaped grooves 3 have been formed with the proper pitch.
The conventional method is disadvantageous because the grooves 3 must be formed one-by-one on the light guide panel. Considerable machine and operator time is required. As a result, the lead time and manufacturing cost of the backlight manufacturing process is somewhat high.
Additionally, with the reciprocating movement of the slider along the guide rail, the art table must be indexed by 1 pitch to form the parallel V-shaped grooves 3 on the light guide panel. This indexing typically requires that the table be moved in a direction 90 degrees from the horizontal motion of the slider. This indexing requires additional time for the formation of each groove. As a result, still more time is required to complete formation of the V-shaped grooves 3 on the light guide panel.
Furthermore, the conventional technique utilizes only a single pin to manufacture all of the V-shaped grooves 3. With such heavy use, it is inevitable for the pin to wear out after a comparatively short lifetime. Thus, frequent maintenance of the V-cutter is required, and more light guide panels may need to be scrapped or reworked due to processing with worn-out pins.
The present invention provides a system and method for solving the problems presented by known V-cutters. One object of the invention is to simultaneously form V-shaped grooves through the use of a plurality of pins corresponding to the grooves on the light guide panel.
Another object of the present invention is to provide a V-cutter with an enhanced operating rate, in which pins broken during operation of the cutter are easily and rapidly replaced with new pins.
A further object of the present invention is to provide a V-cutter in which a load applied on the pins can be maintained at the desired level by adjusting an elastic member and a height control bolt disposed on a buffer plate or slant of the buffer plate, while still permitting alteration of the pin loading in response to the pitch of the grooves to be formed.
In order to achieve the objects of the invention, there is provided a pin kit for V-cutter for forming a plurality of V-shaped grooves spaced apart according to a desired interval on a light guide panel. The pin kit may comprise a buffer plate fixed to the lift piece, an elastic member fixed in the longitudinal direction at a bottom end thereof, a guide plate having insertion holes for a plurality of pins that will be in contact with the elastic member, and a pin to be inserted into an insertion hole on the guide plate for forming V-shaped grooves on the light guide panel.
These and other objects, features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.